If you are like me when it comes to remembering little things this might be of help.
I have to convert inches to pixels when I make a digital collage. The first thing you need to know is the size you want to create.
I use the standard photo sizes, 4×6, 5×7, 8×10. I thought a cute and simple cheat sheet would help me to remember.
An awesome and FREE tool I have discovered is GIMP 2. Its a fairly simple program with great results.
Hope you find this useful!